The invention belongs to the technical field of rolling mills, and discloses a double-circuit power supply frequency conversion transmission system. The system comprises a first frequency conversion main circuit and a second frequency conversion main circuit which are used for supplying power to a first winding and a second winding of a motor respectively. A parallel switch is respectively connected with the output end of the first frequency conversion main circuit and the output end of the second frequency conversion main circuit and is used for realizing parallel connection of a first winding and a second winding of the motor. Under the condition that only one of the first frequency conversion main circuit and the second frequency conversion main circuit fails, the parallel switch is switched on. At this time, the power is supplied to a parallel circuit of the first winding and the second winding of the motor in a capacity reduction manner through the non-failed one of the first frequency conversion main circuit and the second frequency conversion main circuit. According to the double-circuit power supply frequency conversion transmission system, under the condition that a frequency conversion main circuit of a continuous mill breaks down, the rollers of the continuous mill can still be kept rotating. The occurrence of steel scratches is avoided.